PCT Published International Application No. 96/32579 describes a method for the model-based determination of the air mass flowing into the cylinders of an internal combustion engine. The air mass actually flowing into the cylinder is calculated with the aid of an intake-manifold-fill model which, from the following input variables: throttle-valve opening angle, ambient pressure and parameters that represent the valve timing, delivers a load value, based on which, the injection time is determined. Both the intake-manifold pressure and the ambient pressure are modeled in the method indicated.
A device for controlling an internal combustion engine is described in German Published Patent Application No. 198 44 086. Internal combustion engine 1 has at least one cylinder, an intake tract and a tank ventilation device that communicates with the intake tract. A dynamic model of the internal combustion engine is provided for calculating the intake-manifold pressure and/or a mass flow into the cylinder of the internal combustion engine. The model is a function in particular of the mass flow through a throttle valve and a mass flow resulting from an internal exhaust-gas recirculation. In this instance, the intake-manifold pressure is modeled as a function of these two variables.
Moreover, internal combustion engines having external exhaust-gas recirculation are already sufficiently known, as well. It is the external exhaust-gas recirculation that is meant when talking in the following about exhaust-gas recirculation.